With high grade coke becoming scarcer and much more expensive, the need for its conservation continues to grow. Various methods have been tried to diminish coke consumption without much success. The Coal Reactor in its ability to generate clean carbon monoxide quite economically, even from poor quality fossil fuels, provides the basis for achieving this goal. An elementary theory allows an estimate of the coke saving possible under reasonable operating conditions with resulting diminished impurities in pig iron. A more illuminating theory based upon complete chemical reactions that are energetically self-sustaining yields the same simple formula in the limit where no direct ore reduction occurs.
The relationship deduced from the cost effectiveness of having steam coal burned in the Coal Reactor to generate CO and using correspondingly less coke in the blast furnace is: EQU D=(2Wd.sub.1 +Vd.sub.2)/(2W+V)
Where V and W are the relative amounts of CO and O.sub.2 and d.sub.2 and d.sub.1 denote the cost for steam coal and coke, respectively. In the limit of V.fwdarw.0, the cost for the coke alone enters; quite clearly at some critical value of the CO/O.sub.2 ratio, fed via the tuyeres into the combustion zone, an inadequate heat balance occurs beyond which no further coke saving is possible.
Thus, to be sure that a realistic case is employed in estimating V, the composition 79% (by volume) CO and 21% O.sub.2 is chosen, corresponding to the satisfactory heat balance for the conventional air blown blast furnace; in the example considered, oxygen rather than air is mixed with CO in the combustion process. For d.sub.1 =$100/ton and d.sub.2 =$30/ton, the value of D becomes 55/ton, reflecting an effective addition to the blast furnace of a mix of approximately 35% coke and 65% steam coal. However, by the device of burning cheaper coal in a separate reaction vessel, the Coal Reactor, a greater dilution of the coke is obtainable than is what is possible otherwise, since the direct addition of coal to the blast furnace is limited to about 15%. Beyond this range, the mechanical strength for the charge column is too greatly diminished, related to a significant reason why coke must be used instead of coal in the first place.
Generating a portion of the CO outside the blast furnace further means cleaner operation with proportionately less sulfur and other impurities in the pig iron itself, a circumstance favorable for production of higher quality steel. A much more sophisticated theory of the blast furnace underlies the present innovation. An entirely new discipline of econochemistry has been discovered of which econometallurgy is but a part. The competition between direct and indirect ore reduction, together with the slag chemistry out of which the energetics and diagnostics derive can thus be taken into account.
All this relates to the correct manner of evaluating the materials/energy balance for the blast furnace which today still rests on the chemical engineering and process embodiment of uncoupled reactions deriving from the Lavoisier concept of independent balanced chemical equation. The present invention cannot be properly understood in the old light, and perhaps explains why blast furnace technology has languished.